Partial Chemical Plating Technique for Apertures of Aluminum Radiator

ABSTRACT

This invention involves the technical area of chemical plating in aluminum radiators, referring specifically to the partial chemical plating technique in the inner cavity of aluminum radiator. It undergoes the inner cavity shielding before zinc impregnation and continues chemical oxidization in other parts in the chemical the based on the existing oxidization trough, making the unshielded area unable to sediment a layer of zinc and be plated with nickel and phosphors alloy. Then, it is applied with enclosure technique. The chemical oxidization and enclosure enable the sections other than the inner cavity in the aluminum radiator to be covered with a layer of oxidization film against erosion from acid and alkali, so the sections covered with a oxidization film will not accumulate a layer of zinc nor be plated with nickel and phosphor alloy in the subsequent zinc impregnation and nickel plating. Only the surface of the inner cavity is plated with nickel and phosphor alloy. The technique in this invention is simple and easy to achieve, with only the walls in inner cavity being plated with nickel and phosphor alloy, which can save up nickel and effectively cut the aluminum radiators&#39; costs.

CROSS REFERENCE TO THE RELATED PATENT APPLICATION

This application claims the priority of the Chinese patent application No. 200710029095.X with filing date of Jul. 11, 2007.

FIELD OF THE INVENTION

This invention involves the technological area of chemical plating techniques to aluminum radiators, referring specifically to partial chemical-plating techniques of the inner cavity in the aluminum radiators.

BACKGROUND OF THE INVENTION

The stacking of aluminum sheet that is processed by machines forms aluminum radiators, while some of the aluminum radiator are intervened, there are some inner cavity in the aluminum radiators, the quantity being around 1-3 and the diameter being around 6˜8 mm. The inner cavity is reserved for the copper heat tubes which are put inside them. Since the weldability between copper and aluminum is poor, it is necessary to plate a layer of nickel-phosphorus weldable alloy in the inner cavity to connect the copper heat tubes and inner cavity.

On the aluminum surface, it is easy to form the natural oxidization film, which is not good for the electrodeposit or chemical plating of aluminum. For the chemical plating on the aluminum surface, there should be a preplating process for the aluminum to be plated. The current regular preplating is the double galvanization technique. See the attached pic 1 of the current ordinary chemical plating of nickel-phosphorus alloy. The procedures are as brief as the following:

Step 1: degreasing, removing the oil stain on the aluminum radiator surface.

Step 2: water rinsing, cleaning the aluminum radiator

Step 3: weak erosion, putting the aluminum radiator in the lye and conducting weak erosion on the aluminum radiator surface.

Step 4: water rinsing, cleaning the aluminum radiator

Step 5: exposure to light, putting the aluminum radiator in the acid liquor and exposing it to light.

Step 6: water rinsing, cleaning the aluminum radiator;

Step 7: the first galvanization, putting the aluminum radiator in the lye containing the zincates for the first galvanization.

Step 8: water rinsing, cleaning the aluminum radiator

Step 9: removing the zinc, putting the aluminum radiator in the acid liquor for zinc removal.

Step 10: water rinsing, cleaning the aluminum radiator;

Step 11: the second galvanization, putting the aluminum radiator in the lye with zincates for the second galvanization;

Water rinsing, cleaning the aluminum radiator;

Step 13: electrodeposits the nickel and phosphor alloy, putting the aluminum radiator in the chemical electrodeposits trough of nickel and electrodeposits the nickel and phosphor on the aluminum radiator surface.

Water rinsing, cleaning the aluminum radiator;

Step 15: drying

Step 16: parching

Step 17: finished products

The above process flow can be simplified as: preplating 1, galvanization 2, electrodeposit nickel-phosphorus alloy, post-treatment, 3. Finished products.

After the aluminum radiator is chemical plated with nickel-phosphorus alloy or plated, the whole aluminum radiator is plated with nickel-phosphorus alloy, including the welding section and the non-welding section of the aluminum radiator; the non-welding section of the aluminum radiator does not need plating. The costs for nickel and phosphor alloy are high, causing the price of aluminum or radiators stay high as always.

SUMMARY OF THE INVENTION

The purpose of this invention aims to provide partial chemical plating technique for the inner cavity in aluminum radiator regarding to the deficiency of above techniques. This technique only plates a layer of weldable nickel-phosphorus alloy to the wall surface of inner cavity in the aluminum radiators, which is simple and easy for implementation, saving nickel and effectively reducing the product costs.

To achieve the aforesaid goal, some partial chemical plating technique in the inner cavity of aluminum radiator with characteristics as included in the following steps:

Step 1: pre-treatment for aluminum radiator, then go on with oil removal, water rinsing, weak erosion, water rinsing, exposure to light and water rinsing one by one for the aluminum radiator.

Step 2: shielding the inner cavity. Take a rubber tube with greater length and smaller diameter than the inner cavity. One end of the tube is sealed and the other end is connected to the aerator. Put the rubber tube into the inner cavity of aluminum radiator and charge the tube with air through the aerator. The tube exposes and presses to the wall of inner cavity, thus shielding the inner cavity.

Step 3: chemical oxidization. After the chemical oxidization, the aluminum radiators' surface that is under the trough surface is covered with a layer of colorless porous oxidization film. The inner cavity is not because of the shielding from rubber tube.

Step 4: water rinsing.

Step 5: enclosure. Put the whole aluminum radiator into the enclosure trough containing the water solutions with sealing compound. When the aluminum radiator is enclosed, the holes in the porous oxidization film on the aluminum radiator's surface are filled up with sealing compound, thus forming a layer of oxidization film against erosion from acid and alkali on the aluminum's surface. There is no change in the inner cavity of aluminum radiator due to the shielding of rubber tube, which remains aluminum.

Step 6: water rinsing

Step 7: remove the shielding in inner cavity, getting the rubber tube out of the aerator and release the gas in the tube which then resume the original shape. Remove the rubber tube from the inner cavity.

Step 7: water rinsing

Step 8: exposure to light

Step 9: water rinsing

Step 10; zinc impregnation. Go on with the first galvanizing, water rinsing, zinc removal (washed in acid), water rinsing, the second galvanization, water rinsing; only the walls in the inner cavity is plated with zinc, while other parts of the aluminum radiator do not accumulate a layer of zinc.

Step 11: chemical plating of nickel and phosphor alloy. Continue with the chemical nickel-plating in the aluminum radiator. Only the walls in inner cavity of the aluminum radiator are plated with nickel and phosphor alloy, while other sections won't.

Step 12: post-treatment. Continue with water rinsing, drying and parching in the aluminum radiator.

Step 13: finished products.

This invention is based on the current processes, conducting shielding in the inner cavity before the galvanization process of the aluminum radiators. Then put it into the chemical oxidization trough to chemically oxidize other sections, making the non shielded sections unable to accumulate zinc layer or be plated with nickel-phosphorus alloy. Then apply the enclosure process to it. When the inner cavity is shielded, the inner cavity wall is not oxidized and it is enclosed and remains aluminum. When the shielding is removed, go on with subsequent galvanization and chemical nickel-phosphorus plating process. The chemical oxidization and enclosure cover a oxidization film against the erosion from acid and alkali on the sections other than the inner cavity wall, so the sections other than inner cavity will not accumulate zinc during the following galvanization and nickel-plating, nor the nickel-phosphorus alloy. Only the inner cavity surface is plated with a weldable nickel-phosphorus alloy, which connects the copper heat tube and the aluminum radiator firmly. It saves nickel and also reduces the aluminum radiators' costs.

To sum up, the process is simple and easy to be carried out, only plating a weldable nickel-phosphorus alloy layer on the inner cavity wall. It can save the metals such as nickel and reduce the costs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: the technical Process Flow of the current nickel-electrodeposit of current radiators

FIG. 2: the technical process flow of this invention

PREFERRED EMBODIMENTS FOR CARRYING OUT THE INVENTION

To further unveil this invention, the following will give the illustration together with attach Pic 2, including the following procedures:

Step 1: conducting preplating to the aluminum radiator, then continue with the oil removal, water rinsing, weak erosion (with lye), water rinsing, exposure to lighting (with acid), water rinsing; each procedure for the preplating in this invention is the same as the current process technique in the current pre-treatment.

Step 2: inner cavity shielding. Take a rubber tube with greater length and smaller diameter than the inner cavity. One end of the tube is sealed and the other end is connected to the aerator. Put the rubber tube into the inner cavity of aluminum radiator and charge the tube with air through the air compressor, in whose case the aerator is connected with the air compressor. The tube exposes and presses to the wall of inner cavity, thus shielding the inner cavity. When it is charged with air, disconnect the aerator with the air compressor. After that, the tube remains exposed and pressing to the wall in the inner cavity, which can effectively prevent various chemical solutions from touching the wall of inner cavity.

Step 3: chemical oxidation. Put the whole aluminum radiator into the chemical oxidization trough containing the solutions with oxidant. After the chemical oxidization, the surface of aluminum radiators is covered with a layer of colorless porous oxidization film. The inner cavity is shielded by the rubber tube, so the oxidants cannot touch the inner cavity surface of the aluminum radiators. The mentioned oxidants are organic amine, which are trolamine or formamine. After the chemical oxidization, the aluminum radiators' surface that is under the trough surface is covered with a layer of colorless porous oxidization film. The inner cavity remains aluminum.

The solution temperature is 80-95° C.; the time for oxidization is 8-30 min. the thickness of the porous oxidization film after oxidization is 0.5-5 micron.

Step 4: water rinsing, cleaning the aluminum radiator

Step 5: enclosure (filled up), putting the aluminum radiator in the enclosed trough with water solution containing sealing compound; the mentioned sealing compound is boric acid; after the aluminum radiator is enclosed, the holes of porous oxidization film on the aluminum radiator surface is filled up with the sealing compound in the enclosed trough. An oxidization film is formed on the aluminum radiator surface that is against the erosion of acid and alkali. The inner cavity of aluminum radiators remain aluminum thanks to the shielding from rubber tube. Here, the temperature of water solution containing sealing compound is around 85-95° C. and the enclosure time is 8-30 min.

The porous oxidization film formed on the aluminum radiator surface in Step 3 cannot withstand the erosion of acid and alkali, so the base of aluminum radiator will accumulate a layer of zinc due to the erosion of alkali in the zincates. Thus, the aluminum radiator covered with a layer of zinc can be plated with nickel-phosphorus alloy in the trough of chemical nickel-plating. The holes in this porous oxidization film should be filled up with filling to make it against acid and alkali; this procedure is called enclosure.

The enclosure process to fill up the holes in the porous oxidization film utilizing the sealing compound, making it withstand the erosion from acid and alkali. In the subsequent process, sections covered by this oxidization film will not accumulate a zinc layer nor the nickel-phosphorus alloy. However, the inner cavity that is not chemically oxidized is not covered by porous oxidization film and will not be enclosed, remaining aluminum. Only the inner cavity can be plated with zinc layer and nickel-phosphorus alloy in the following processes, thus achieving the purpose of partial chemical oxidization of the inner cavity.

Step 6: water rinsing, cleaning the aluminum radiator

Step 7: remove the inner cavity shielding. After the enclosure process, pull out the aerator from one end of the rubber tube and release the gas in the rubber tube, which resume the original shape. Take out the rubber tube from inner cavity.

Step 8: exposure to light. This process is the same with the current process.

Step 9: water rinsing, cleaning the aluminum radiator

Step 10: Galvanization, then conducting the first galvanization, water rinsing, zinc removal (washed with acid), water rinsing, the second galvanization, water rinsing one by one. The inner cavity wall is accumulated with a layer of zinc in the galvanization process while other sections are covered with a layer of oxidization film. Each process in this procedure is the same as the corresponding current technique.

Step 11: chemical plating with nickel-phosphorus alloy, conducting chemical plating to the aluminum radiator. This process is the same as the current process. Only inner cavity wall on the aluminum radiator is plated with nicked-phosphorus alloy, while other sections are covered with oxidization film. Thus, only the inner cavity wall is accumulated with a layer of zinc and other sections won't be plated with nickel-phosphorus alloy.

Step 12: post-treatment, then conducting water rinsing, drying, parching to the aluminum radiator; each technique in this step is the same as the current existing corresponding technique.

Step 13: finished products.

As shown in the above process, after the techniques in this invention, the weldable nickel-phosphorus alloy is only plated in the wall surface of the inner cavity in aluminum radiators; the other sections are not plated with nickel-phosphorus alloy. The aluminum radiator is only partially plated. The technique is simple and can save the nickel and phosphor alloy.

This invention's technique is based on the current technique. Before the galvanization is applied, inner cavity shielding is applied to the aluminum radiators and then chemical plating is applied to other sections. This makes the non-shielding area unable to neither accumulate a layer of zinc nor be plated with nickel-phosphorus alloy. The procedures can be simplified as: preplating 1, partial chemical oxidization 2, galvanization 3, autocalytic plating of nickel-phosphorus alloy, postplating 4, and finished products.

The above is a better implementation example of the invention. Therefore, all the equivalent changes or embellishment according to the structure, characteristics and principles stated in the patent scope of the invention are included in the patent applicable scope of this invention. 

1. Partial chemical plating technique for apertures of an aluminum radiator comprising the following steps: Step 1: pre-treatment for the aluminum radiator, then go on with oil removal, water rinsing, weak erosion, water rinsing, exposure to light and water rinsing step by step for the aluminum radiator; Step 2: shielding the apertures of the aluminum of the radiator, take a rubber tube with greater length and smaller diameter than the aperture, Seal one end of the tube and connect the other end to an aerator, Put the rubber tube into the aperture of the aluminum radiator and charge the rubber tube with air by the aerator, the expanded tube presses to the wall of the aperture and shields the wall of the aperture; Step 3: chemical oxidization, put the aluminum radiator with shielded apertures into a chemical oxidization trough containing solution with oxidant, after the chemical oxidization, the surface of the aluminum radiator is covered with a layer of colorless porous oxidization film, but the wall of aperture is covered nothing because of the shielding of the rubber tube. Step 4: water rinsing; Step 5: enclosure, put the whole aluminum radiator into the enclosure trough containing water solution with sealing compound, after the aluminum radiator is enclosed, holes in the porous oxidization film on the aluminum radiator's surface are filled up with the sealing compound, thus a layer of oxidization film is formed on aluminum surface to against erosion from acid and alkali, there is no change for the wall of aperture of the radiator due to the shielding of rubber tube, which remains of aluminum; Step 6: water rinsing; Step 7: remove the shielding from the aperture, get the rubber tube out of the aerator and release gas to resume the rubber tube in original shape, remove the rubber tube from the aperture; Step 7: water rinsing; Step 8: exposure to light; Step 9: water rinsing; Step 10: zinc impregnation, make first galvanizing for the radiator, than water rinsing, continue with zinc removal by washing the galvanized radiator in acid, then water rinsing, continue with second galvanization, then water rinsing, only the wall of aperture is plated with zinc, while other surfaces of the radiator do not accumulate a layer of zinc; Step 11: chemical plating of nickel and phosphor alloy, Continue with the chemical nickel and phosphor-plating for the radiator, only the wall of the aperture is plated with nickel and phosphor alloy, while other surfaces of the radiator won't. Step 12: post-treatment, continue with water rinsing, drying and parching for the radiator. Step 13: finished products.
 2. The partial chemical plating technique of claim 1, wherein the aerator is connected with an air compressor for charging gas into the rubber tube.
 3. The partial chemical plating technique of claim 1, wherein the oxidants in the chemical oxidization in the Step 3 are organic amine comprising trolamine and formamine.
 4. The partial chemical plating technique of claim 1, wherein in the chemical oxidization in Step 3, the solution temperature is 80-95° C., the time for oxidization is 8-30 min, the thickness of the porous oxidization film after the chemical oxidization is 0.5-5 micron
 5. The partial chemical plating technique of claim 1, wherein in the enclosure in Step 5, the sealing compound is boric acid.
 6. The partial chemical plating technique of claim 1, wherein in the enclosure in Step 5, the temperature of the water solution with sealing compound is 85-95° C., The enclosure time is 8-30 min. 